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John is twice as old as mary. the sum of their ages is 21. how old is mary? let j = john's age and m = mary's age. select the system equations that represents the prob…
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John is twice as old as mary. the sum of their ages is 21. how old is mary? let j = john's age and m = mary's age. select the system equations that represents the prob…
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Jul 15, 2017
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john is twice as old as mary. the sum of their ages is 21. how old is mary? let j = john's age and m = mary's age. select the system equations that represents the problem.
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Hello,
let's assume j the john's age, m the mary's age.
"John is twice as old as mary"==>j=2*m
"the sum of their ages is 21" ==>j+m=21
==>2*m+m=21
==>3m=21
==>m=7
and j=21-7=14
Pindatjuh
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Jul 20, 2017
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